rust-index: add a function to convert PyObject index for hg-core Function in hg-core need something implementing the `Graph` trait. Right now, the `hg-cpython` entry points directly turn the PyObject passed as argument into a `cindex::Index`. However, if we start having the option to use an Index in Rust, we need to dispatch between the different possible PyObject we could receive. So move the "duplicate" call into a unified function. When time come. It will be easy to update the logic of all interface when the time come. Differential Revision: https://phab.mercurial-scm.org/D7653

test: extract some generic data and utility from test-rust-ancestor.py We will reuse this for more tests related to revlog index. In pratice this series of changesets add an index implementation provided from Rust and we want to be able to test it. Differential Revision: https://phab.mercurial-scm.org/D7652

patch: fix header.__repr__() to not have `b''` prefixes in file names Spotted by Denis Laxalde. Differential Revision: https://phab.mercurial-scm.org/D7695

cmdutil: allow native string as input to check_at_most_one_arg() We seem to always convert **opts args to use bytes as keys early on in Mercurial core, but I'm not sure we have good reason to do that, and not all extensions do that. It's therefore helpful to be able to pass in a native string to check_at_most_one_arg(). Differential Revision: https://phab.mercurial-scm.org/D7699

cmdutil: return underscore-separate name from check_at_most_one_arg() As noticed by Yuya, when I changed the function (during review) to work with underscore-separated names as input, I forgot to make sure the returned name was also underscore-separated. We don't have any cases where it matters yet, but it should still clearly be fixed. Instead of converting the hyphen-separated value we already have in `previous`, I'm changing it so we convert to the underscore-separated values to be hyphen-separated only when we need to display them. This will also help a coming change where we allow the inputs to native strings instead only bytes. Differential Revision: https://phab.mercurial-scm.org/D7698

rebase: restore i18n of a hint message As noticed by Yuya, I lost the _() call in 71fee4564410 (rebase: use rewriteutil.precheck() instead of reimplementing it, 2019-12-18). Differential Revision: https://phab.mercurial-scm.org/D7697

status: make unresolved files always be in the morestatus structured output We don't know the status of those files, only that they're unresolved, so we don't output the status for those - any code parsing this will have to be tolerant to that. Differential Revision: https://phab.mercurial-scm.org/D7668